The present invention relates to an image reading apparatus and, particularly, to such an apparatus which can be used for not only a micro-array image detecting system but also an autoradiographic image detecting system, a chemiluminescenct image detecting system, an electron microscopic image detecting system and a radiographic diffraction image detecting system using a stimulable phosphor sheet, and a fluorescent image detecting system.
An autoradiographic image detecting system is known that uses as a detecting material for detecting radiation a stimulable phosphor which can absorb, store and record the energy of radiation when it is irradiated with radiation and which, when it is then stimulated by an electromagnetic wave having a specified wavelength, can release a stimulated emission whose light amount corresponds to the amount of radiation with which it was irradiated. A method associated with this detecting system comprises the steps of: introducing a radioactively labeled substance into an organism, using the organism or a part of the tissue of the organism as a specimen, placing the specimen and a stimulable phosphor sheet formed with a stimulable phosphor layer together in layers for a certain period of time, storing and recording radiation energy in a stimulable phosphor contained in the stimulable phosphor layer, scanning the stimulable phosphor layer with an electromagnetic wave to excite the stimulable phosphor, photoelectrically detecting the stimulated emission released from the stimulable phosphor to produce digital image signals, effecting image processing on the obtained digital image signals, and reproducing an image on a displaying means such as a CRT or the like or a photographic film (see, for example, Japanese Patent Publication No. 1-60784, Japanese Patent Publication No. 1-60782, Japanese Patent Publication No. 4-3952 and the like).
There is also known a chemiluminescent image detecting system using as a detecting material for detecting light a stimulable phosphor which can absorb, store and record the light energy when it is irradiated with light and which, when it is then stimulated by an electromagnetic wave having a specified wavelength, can release stimulated emission whose light amount corresponds to the amount of light radiation with which it was irradiated. A method associated with the chemiluminescent image detecting system comprises the steps of: selectively labeling a fixed high molecular substance such as a protein or a nucleic acid sequence with a labeling substance which generates chemiluminescent emission when it contacts a chemiluminescent substance, contacting the high molecular substance selectively labeled with the labeling substance and the chemiluminescent substance, photoelectrically detecting the chemiluminescent emission in the wavelength of visible light generated by the contact of the chemiluminescent substance and the labeling substance and producing digital image signals, effecting image processing thereon, and reproducing a chemiluminescent image on a display means such as a CRT or a recording material such as a photographic film, thereby obtaining information relating to the high molecular substance such as genetic information (see, for example, U.S. Pat. No. 5,028,793, British Patent Publication GB No. 2,246,197A and the like).
There are further known an electron microscopic image detecting system and a radiographic diffraction image detecting system. A method of using these two systems comprises the steps of: employing, as a detecting material for an electron beam or radiation, a stimulable phosphor which can absorb and store the energy of an electron beam or radiation upon being irradiated therewith and release a stimulated emission whose amount is proportional to that of the received electron beam or radiation upon being stimulated with an electromagnetic wave having a specific wavelength range, irradiating a metal or nonmetal specimen with an electron beam and effecting elemental analysis, composition analysis or structural analysis of the specimen by detecting a diffraction image or a transmission image, or irradiating the tissue of an organism with an electron beam and detecting an image of the tissue of the organism, or irradiating a specimen with radiation, detecting a radiographic diffraction image and effecting structural analysis of the specimen (see, for example, Japanese Patent Application Laid Open No. 61-51738, Japanese Patent Application Laid Open No. 61-93538, Japanese Patent Application Laid Open No. 59-15843 and the like).
Unlike the system using a photographic film, according to these systems using the stimulable phosphor as a detecting material for an image, development, which is chemical processing, becomes unnecessary. Further, it is possible to reproduce a desired image by effecting image processing on the obtained image data and effect quantitative analysis using a computer. Use of a stimulable phosphor in these processes is therefore advantageous.
On the other hand, a fluorescence system using a fluorescent substance as a labeling substance instead of a radioactively labeling substance in the autoradiographic image detecting system is known. According to this system, it is possible to study a genetic sequence, study the expression level of a gene, and to effect separation or identification of protein or estimation of the molecular weight or properties of protein or the like. For example, this system can perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis after a fluorescent dye was added to a solution containing a plurality of DNA fragments to be distributed, or distributing a plurality of DNA fragments on a gel support containing a fluorescent dye, or dipping a gel support on which a plurality of DNA fragments have been distributed by means of electrophoresis in a solution containing a fluorescent dye, thereby labeling the electrophoresed DNA fragments, exciting the fluorescent dye by a stimulating ray to cause it to release fluorescent light, detecting the released fluorescent light to produce an image and detecting the distribution of the DNA fragments on the gel support. This system can also perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis, denaturing the DNA fragments, transferring at least a part of the denatured DNA fragments onto a transfer support such as a nitrocellulose support by the Southern-blotting method, hybridizing a probe prepared by labeling target DNA and DNA or RNA complementary thereto with the denatured DNA fragments, thereby selectively labeling only the DNA fragments complementary to the probe DNA or probe RNA, exciting the fluorescent dye by a stimulating ray to cause it to release fluorescent light, detecting the released fluorescent light to produce an image and detecting the distribution of the target DNA on the transfer support. This system can further perform a process including the steps of preparing a DNA probe complementary to DNA containing a target gene labeled by a labeling substance, hybridizing it with DNA on a transfer support, combining an enzyme with the complementary DNA labeled by a labeling substance, causing the enzyme to contact a fluorescent substance, transforming the fluorescent substance to a fluorescent substance having fluorescent light releasing property, exciting the thus produced fluorescent substance by a stimulating ray to release fluorescent light, detecting the fluorescent light to produce an image and detecting the distribution of the target DNA on the transfer support. This fluorescence detecting system is advantageous in that a genetic sequence or the like can be easily detected without using a radioactive substance.
Further, a micro-array image detecting system has been recently developed, which comprises the steps of using a spotter device to drop at different positions on the surface of a carrier such as a slide glass plate, a membrane filter or the like a specific binding substance, which can specifically bind with a substance derived from a living body such as hormone, a tumor marker, enzyme, antibody, antigen, abzyme, other proteins, a nuclear acid, cDNA, DNA, RNA and the like and whose sequence, base length, composition and the like are known, thereby forming a number of independent spots, hybridizing the specific binding substance with a substance derived from a living body such as hormone, a tumor marker, enzyme, antibody, antigen, abzyme, other proteins, a nuclear acid, cDNA, DNA or mRNA, which is gathered from a living body by extraction, isolation or the like or is further subjected to chemical processing, chemical modification or the like and which is labeled with a labeling substance such as a fluorescent substance, dye or the like, thereby forming a micro-array, irradiating the micro-array with a stimulating ray, photoelectrically detecting light such as a fluorescence emitted from a labeling substance such as a fluorescent substance, dye or the like, and analyzing the substance derived from a living body. This micro-array image detecting system is advantageous in that a substance derived from a living body can be analyzed in a short time period by forming a number of spots of a specific binding substance at different positions of the surface of a carrier such as a slide glass plate with high density and hybridizing them with a substance derived from a living body and labeled with a labeling substance.
Since the autoradiographic image detecting system, the chemiluminescent image detecting system, the image detecting system using an electron microscope, the radiographic diffraction image detecting system, the fluorescent image detecting system and the micro-array image detecting system are used for the similar purposes, it is desirable to develop an image reading apparatus which can be used in common for all of these systems. In fact, an image reading apparatus which can be used in common for the autoradiographic image detecting system, the chemiluminescent image detecting system, the image detecting system using an electron microscope and the radiographic diffraction image detecting system using a stimulable phosphor sheet, and the fluorescent image detecting system has been already developed, and an image reading apparatus which can be used in common for the chemiluminescent image detecting system capable of forming a chemiluminescent image without using a stimulable phosphor sheet and the fluorescent image detecting system has also been already developed.
However, in the fluorescent image detecting system, since fluorescent light emitted from a fluorescent substance contained in a gel support or a transfer support and stimulated is detected, the image reading apparatus has to include an optical system having a great focal depth, and in the autoradiographic image detecting system, the chemiluminescent image detecting system, the image detecting system using an electron microscope and the radiographic diffraction image detecting system using a stimulable phosphor sheet, since stimulated emission is emitted from stimulable phosphors in a stimulable phosphor layer formed on the surface of the stimulable phosphor sheet, the image reading apparatus has to include an optical system having relatively great focal depth. To the contrary, in an image reading apparatus for the micro-array image detecting system, since a micro-array image is photoelectrically detected by detecting fluorescent light from a fluorescent substance labeling a substance derived from a living body hybridized with a specific binding substance on the surface of a slide glass plate, a membrane filter or the like, it is required to employ a confocal optical system for improving the S/N ratio.
Therefore, in the image reading apparatus for the micro-array image detecting system, since the focal depth of the optical system thereof is shallow, a micro-array image can be read with a high S/N ratio but it is impossible to produce image data having sufficiently high signal intensity by photoelectrically detecting fluorescent light emitted from a fluorescent substance contained in a gel support or a transfer support or stimulated emission emitted from a stimulable phosphor sheet.
In particular, in the image reading apparatus for the micro-array image detecting system, it is often required to carry out a preliminary test to read a fluorescent image of a specimen electrophoresed on a gel support or a transfer support. However, a conventional image reading apparatus for the micro-array image detecting system cannot read such a fluorescent image with high sensitivity and, therefore, another type of an image reading apparatus has to be used for reading such a fluorescent image.
It is therefore an object of the present invention to provide an image reading apparatus which can be used for not only a micro-array image detecting system but also an autoradiographic image detecting system, a chemiluminescent image detecting system, an image detecting system using an electron microscope and a radiographic diffraction image detecting system using a stimulable phosphor sheet and a fluorescent image detecting system.
The above other objects of the present invention can be accomplished by an image reading apparatus comprising at least one laser stimulating ray source, a stage on which two or more kinds of image carriers can selectively be placed, a scanning mechanism for scanning the image carrier with a laser beam emitted from the at least one laser stimulating ray source, thereby stimulating the image carrier, a light detector for photoelectrically detecting light emitted from the image carrier in response to stimulation by the laser beam and a confocal optical system for leading light emitted from the image carrier to the light detector, the image reading apparatus further comprising a confocal switching means having diameter-variable pinhole means and disposed between the confocal optical system and the light detector and whose pinhole diameter is variable.
According to the present invention, light emitted from the image carrier is guided by the confocal optical system and detected by the light detector via the confocal switching means having diameter-variable pinhole means. Therefore, when the image reading apparatus is used for the micro-array image detecting system, a micro-array image can be read with a high S/N ratio by focusing light emitted from the surface of a slide glass plate, a membrane filter or the like onto a pinhole having a small diameter of the confocal switching means using the confocal optical system and detecting it by the light detector, and when the image reading apparatus is used for photoelectrically reading fluorescent light emitted from the inside of a gel support or a transfer support or stimulated emission emitted from the inside of a stimulable phosphor layer formed on a stimulable phosphor sheet, image data having sufficiently high signal intensity can be produced by causing the light detector to detect light emitted from the image carrier via a pinhole having a large diameter of the confocal switching means.
In the present invention, diameter-variable pinhole means as termed here includes not only a plurality of pinholes having different diameters but also means having at least one pinhole and retracted so that no pinhole is located in the light path.
In a preferred aspect of the present invention, the confocal switching means is constituted by a rectangular plate member formed with a plurality of pinholes having different diameters and the image reading apparatus further comprises drive means for sliding the confocal switching means so that the respective pinholes can be selectively located in a path of light emitted from the image carrier.
According to this preferred aspect of the present invention, a desired pinhole can be located very easily by selecting the desired pinhole in accordance with the kind of image carrier and sliding the confocal switching means. Therefore, when the image reading apparatus is used for the micro-array image detecting system, a micro-array image can be read with a high S/N ratio very easily by focusing light emitted from the surface of a slide glass plate, a membrane filter or the like onto a pinhole having a small diameter of the confocal switching means using the confocal optical system and detecting it by the light detector and when the image reading apparatus is used for photoelectrically reading fluorescent light emitted from the inside of a gel support or a transfer support or stimulated emission emitted from the inside of a stimulable phosphor layer formed on a stimulable phosphor sheet, image data having sufficiently high signal intensity can be produced very easily by causing the light detector to detect light emitted from the image carrier via a pinhole having a large diameter of the confocal switching means.
In another preferred aspect of the present invention, the confocal switching means is constituted by a circular plate member formed with a plurality of pinholes having different diameters and the image reading apparatus further comprises drive means for rotating the confocal switching means so that the respective pinholes can be selectively located in a path of light emitted from the image carrier.
According to this preferred aspect of the present invention, a desired pinhole can be located very easily by selecting the desired pinhole in accordance with the kind of image carrier and rotating the confocal switching means. Therefore, when the image reading apparatus is used for the micro-array image detecting system, a micro-array image can be read with a high S/N ratio very easily by focusing light emitted from the surface of a slide glass plate, a membrane filter or the like onto a pinhole having a small diameter of the confocal switching means using the confocal optical system and detecting it by the light detector and when the image reading apparatus is used for photoelectrically reading fluorescent light emitted from the inside of a gel support or a transfer support or stimulated emission emitted from the inside of a stimulable phosphor layer formed on a stimulable phosphor sheet, image data having sufficiently high signal intensity can be produced very easily by causing the light detector to detect light emitted from the image carrier via a pinhole having a large diameter of the confocal switching means.
In another preferred aspect of the present invention, the confocal switching means is constituted by an iris diaphragm whose center portion is located in a path of light emitted from the image carrier and the image reading apparatus further comprises a drive means for adjusting a diameter of the iris diaphragm.
According to this preferred aspect of the present invention, a desired pinhole can be located very easily by using the drive means to adjust the diameter of the iris diaphragm in accordance with the kind of image carrier so as to make it equal to a desired. Therefore, when the image reading apparatus is used for the micro-array image detecting system, a micro-array image can be read with a high S/N ratio very easily by focusing light emitted from the surface of a slide glass plate, a membrane filter or the like onto a pinhole having a small diameter of the confocal switching means using the confocal optical system and detecting it by the light detector, and when the image reading apparatus is used for photoelectrically reading fluorescent light emitted from the inside of a gel support or a transfer support or stimulated emission emitted from the inside of a stimulable phosphor layer formed on a stimulable phosphor sheet, image data having sufficiently high signal intensity can be produced very easily by causing the light detector to detect light emitted from the image carrier via a pinhole having a large diameter of the confocal switching means.
In a further preferred aspect of the present invention, the confocal switching means is constituted by a plate-like member formed with a single pinhole and the image reading apparatus further comprises a drive means for sliding the confocal switching means between a confocal position where the single pinhole is located in a path of light emitted from the image carrier and a retracted position where the single pinhole is retracted from the path of light emitted from the image carrier.
According to this preferred aspect of the present invention, the confocal switching means can be moved by the drive means so that the single pinhole can be located in the path of light emitted from image carrier. Therefore, when the image reading apparatus is used for the micro-array image detecting system, a micro-array image can be read with a high S/N ratio very easily by focusing light emitted from the surface of a slide glass plate, a membrane filter or the like onto a pinhole having a small diameter of the confocal switching means using the confocal optical system and detecting it by the light detector and when the image reading apparatus is used for photoelectrically reading fluorescent light emitted from the inside of a gel support or a transfer support or stimulated emission emitted from the inside of a stimulable phosphor layer formed on a stimulable phosphor sheet, image data having sufficiently high signal intensity can be produced very easily by causing the light detector to detect light emitted from the image carrier via a pinhole having a large diameter of the confocal switching means.
In a further preferred aspect of the present invention, the image reading apparatus further comprises a holder sensor for detecting the kind of a holder supporting the image carrier placed on the stage and a confocal switching control means for controlling the drive means in accordance with a detection signal of the holder sensor.
According to this preferred aspect of the present invention, a desired pinhole can be automatically located in the path of light emitted from the image carrier in accordance with the detection signal of the holder sensor. Therefore, when the image reading apparatus is used for the micro-array image detecting system, a micro-array image can be read with a high S/N ratio very easily and reliably by focusing light emitted from the surface of a slide glass plate, a membrane filter or the like onto a pinhole having a small diameter of the confocal switching means using the confocal optical system and detecting it by the light detector, and when the image reading apparatus is used for photoelectrically reading fluorescent light emitted from the inside of a gel support or a transfer support or stimulated emission emitted from the inside of a stimulable phosphor layer formed on a stimulable phosphor sheet, image data having sufficiently high signal intensity can be produced very easily and reliably by causing the light detector to detect light emitted from the image carrier via a pinhole having a large diameter of the confocal switching means.
In a further preferred aspect of the present invention, the two or more kinds of image carriers include at least a DNA micro-array.
In a further preferred aspect of the present invention, the two or more kinds of image carriers include at least one kind of image carrier selected from a group consisting of a support carrying an image of a fluorescent substance produced by a fluorescent image detecting system, a stimulable phosphor sheet carrying an autoradiographic image, a stimulable phosphor sheet carrying an image of an electron microscope, a stimulable phosphor sheet carrying a radiographic diffraction image, and a stimulable phosphor sheet carrying a chemiluminescent image.
The above and other objects and features of the present invention will become apparent from the following description made with reference to the accompanying drawings.